Any discussion of the background art throughout the specification should in no way be considered as an admission that such art is widely known or forms part of common general knowledge in the field.
The utilization of imaging such as PET or SPECT imaging in the in vitro diagnosing of disease is an important undertaking. This is particularly the case with neurodegenerative diseases such as Alzheimer's disease (AD). The interpretation of suitable imagery is important in gaining an understanding and appreciation of treatment of the disease.
The prior art includes many systems for acquisition and analysis of PET and other image modalities. For example, PCT publication WO2008/093057 to Liljat et al. discloses one such system for the analysis of PET and other imagery in the investigation of AD. Another system is disclosed in US Patent Application Publication No. 2006/074290 to Chen Kewei et al. In all such systems, it is desirable to be able to quickly provide diagnostic information on the state of the imagery.
β-amyloid (Aβ) plaques are among the most prevalent pathological characteristics of Alzheimer's disease (AD), which can appear many years before the dementia is diagnosed. The recent development of functional imaging agents makes it possible to assess amyloid deposition in vivo. One promising known radiotracer is Pittsburgh Compound-B (11C-PiB), which binds with high affinity and high specificity to Aβ plaques. It has been shown that AD patients tend to have higher PiB binding in cortical regions than normal controls. Other important Amyloid imaging compounds are being developed such as Florbetapir, and could also be utilized with the present invention.
The assessment of PiB uptake with different tissue types (grey matter, white matter, and CSF) in cortical regions can facilitate the diagnosis and monitoring of the dementia. However, due to the low resolution and the lack of structural information in PET images, the existing approaches usually rely on concurrent MRI images for the determination of tissue regions. Further, the binding pattern of the marker is often unrelated to the underlying tissue structure and can be highly variable. The common process such as those disclosed in Lilja et al. involves a concurrent tissue segmentation on an MRI image and a multi-modular registration between MRI and PET images for each subject.
Although such estimations are relatively accurate, MRI-independent assessment methods are desirable due to clinical settings and the absence of MRI scans due to various reasons (e.g. claustrophobia, metallic implants, etc. . . . ).